Analysis of association between polymorphisms of MTHFR, MTHFD1 and RFC1 genes and efficacy and toxicity of methotrexate in rheumatoid arthritis patients

Abstract

A folate analogue methotrexate (MTX) is the most commonly used disease-modifying drug in the treatment of rheumatoid arthritis. However, the clinical response of RA patients treated with MTX shows interindividual differences and 30% of patients discontinue therapy due to the side effects. In a group of 184 RA patients treated with MTX we have investigated whether polymorphisms in MTHFR (rs1801133, rs1801131), MTHFD1 (rs2236225) and RFC1 (rs144320551) genes may have impact on MTX efficacy and/or adverse drugs effects (ADEs). The efficacy of the MTX therapy has been estimated using the disease activity score in 28 joints (DAS28-ESR) based on EULAR criteria and relative DAS28 values (rDAS28) and all adverse drug events were recorded. Patients were genotyped for selected polymorphism by PCR-RFLP method. According to the EULAR response criteria after 6 months of MTX therapy 146 (79.3%) patients were classified as responders, (17 patients (11.6%) were good and 129 patients (88.4%) were moderate responders) and 38 patients (20.7%) as non-responders. ADEs were observed in 53 (28.8%) patients. The majority of ADEs were mild (36 (19.56%) patients) to moderate (12 (6.25%) patients). Five patients (2.7%) had serious ADEs. Association studies have been conducted between obtained genotypes and the efficacy and toxicity of MTX. We have observed no association between polymorphisms and efficacy or toxicity of MTX in RA patients.